This charming book not only partakes in the recent British wave of popular-yet-reliable science books but also offers the inside view provided by someone who actually helped to shape the subject: Prof. Fortey need not be introduced to anyone researching or just collecting trilobites.
His book has three topics: First, "Trilobite!" reassuringly tells the reader that, with some luck, you actually can preserve a childhood hobby not only as a lifelong fascination but even turn it into a rewarding and respected occupation without (and that's the important point) losing the thrill of it.
Secondly, the author demonstrates by the example of these mostly small, long-extinct little arthropods the astonishing insights to be gained by not ignoring the inconspicuous. Trilobites to the layman's eye look like something you would stomp upon if you found it crawling on the floor, but they actually were the first "real" animals at all, dominated the sea-floor for most of the Paleozoic age, and at the very dawn of evolution some of their species already had complex eyes with lenses correcting for chromatic aberration(!).
With this, Prof. Fortey, thirdly, against widespread public distrust, makes a case for science as a profoundly humane occupation: A scientist is neither the harmless but also superfluous bug-collector of popular cliche nor the brilliant but dangerous seeker for world domination (by means of genetic manipulation or similar), also of popular cliche.
As for style, the book is entertaining, even funny, and well written, although at times a trifle overly fond of literary allusions and quotations. To alleviate the fears of any non-paleozoologist, it almost totally avoids the latinate vocabulary of taxonomy. Thus, it is recommnded not only for trilobite enthusiasts but even more so for anyone interested in a glimpse of how science actually works.